ExpirationInput.validate = function validate (state) {
  var data = value(state.value)

  return Boolean(data) &&
    expiration.month.isValid(data.month) &&
    expiration.year.isValid(data.year) &&
    !expiration.isPast(data.month, data.year)
}
function parse (raw) {
  var parts = raw.match(MM_YY)
  if (!parts) return null

  var rawMonth = parts[1]
  var rawYear = parts[3]

  if (!rawYear || rawYear.length % 2) return null

  return {
    month: expiration.month.parse(rawMonth),
    year: expiration.year.parse(rawYear, rawYear.length < 4)
  }
}